SYNOPSIS

DESCRIPTION

The ganeti software manages physical nodes and virtual instances of a
cluster based on a virtualization software. The current version (2.0)
supports Xen 3.0 (also tested with 3.1) and KVM hypervisors.

QUICKSTART

First you must install the software on all the cluster nodes, either
from sources or (if available) from a package. The next step is to
create the initial cluster configuration, using gnt-clusterinit.
Then you can add other nodes, or start creating instances.

CLUSTERARCHITECTURE

In Ganeti 2.0, the architecture of the cluster is a little more
complicated than in 1.2. The cluster is coordinated by a master daemon
(ganeti-masterd(8)), running on the master node. Each node runs (as
before) a node daemon, and the master has the RAPI daemon running too.
NODEROLES
Each node can be in one of the following states:
master Only one node per cluster can be in this role, and this node is
the one holding the authoritative copy of the cluster
configuration and the one that can actually execute commands on
the cluster and modify the cluster state. See more details under
Clusterconfiguration.
master_candidate
The node receives the full cluster configuration (configuration
file and jobs) and can become a master via the gnt-clustermasterfailover command. Nodes that are not in this state cannot
transition into the master role due to missing state.
regular
This the normal state of a node.
drained
Nodes in this state are functioning normally but cannot receive
new instance, because the intention is to set them to offline or
remove them from the cluster.
offline
These nodes are still recorder in the ganeti configuration, but
except for the master daemon startup voting procedure, they are
not actually contacted by the master. This state was added in
order to allow broken machines (that are being repaired) to
remain in the cluster but without creating problems.
CLUSTERCONFIGURATION
The master node keeps and is responsible for the cluster configuration.
On the filesystem, this is stored under the /var/ganeti/lib directory,
and if the master daemon is stopped it can be backed up normally.
The master daemon will replicate the configuration database called
config.data and the job files to all the nodes in the master candidate
role. It will also distribute a copy of some configuration values via
the ssconf files, which are stored in the same directory and start with
ssconf_ prefix, to all nodes.
JOBS
All cluster modification are done via jobs. A job consists of one or
more opcodes, and the list of opcodes is processed serially. If an
opcode fails, the entire job is failed and later opcodes are no longer
processed. A job can be in one of the following states:
queued The job has been submitted but not yet processed by the master
daemon.
waiting
The job is waiting for for locks before the first of its
opcodes.
canceling
The jos is waiting for locks, but is has been marked for
cancelation. It will not transition to running, but to canceled.
running
The job is currently being executed.
canceled
The job has been canceled before starting execution.
success
The job has finished successfully.
error The job has failed during runtime, or the master daemon has been
stopped during the job execution.

COPYRIGHT

Copyright (C) 2006, 2007, 2008, 2009 Google Inc. Permission is granted
to copy, distribute and/or modify under the terms of the GNU General
Public License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
On Debian systems, the complete text of the GNU General Public License
can be found in /usr/share/common-licenses/GPL.